Various prior art devices have been suggested for transferring articles in an arcuate path and I refer particularly to U.S. Pat. Nos. 3,080,070; 3,593,493; 3,777,906; 4,134,318; and 4,216,689 in which individual articles are handled. The particular problem faced by the present inventors involves the transfer of stacks of plastic articles which are somewhat fragile and flexible from the chutes of a trim press to an underlying conveyor which may be proceeding in a direction at right angles to the axis of the chutes. An apparatus for accomplishing this is shown in the present assignee's U.S. Pat. No. 3,491,633, in an environment in which nested plastic cups are being separated. In the present assignee's U.S. Pat. No. 3,217,576, relatively small diameter lids are being trimmed or separated from the web in the trimming machine.
The present invention is concerned with handling even more difficult to handle stacks of plastic articles of disc-like configuration such as plastic plates, and moving them from the trim press chutes to an underlying conveyor which is, in contrast to the discharge conveyor shown in U.S. Pat. No. 3,491,633, located at a considerably lower level than the trim press chutes.
The apparatus involved in the present invention is, preferably of a portable nature in the sense that it comprises a frame mounted on wheels which permits it to be moved to various locations. It, further, is of the type which utilizes a swingable transfer arm. When handling articles such as stacks of shallowly nested, relatively thin-walled, plastic plates, we have found it expedient, to avoid a multitude of problems, to employ radially contractable and expansible stackgripping members, and to provide such members on a receiver head mounted on the transfer arm assembly for moving the stacks of articles simultaneously in a downward path.
In accordance with the present invention, the receiver or gripping head must travel from a first position axially aligned with the chutes in which the stack gripping members are axially intermeshed therewith in a path having a first horizontally linear increment, then a downward arc, and finally a terminal vertically linear path which deposits the stacks of articles on the conveyor surface. The horizontally axially linear path is necessary to remove the stacks of articles from the stack support chutes which are mounted on the trimming machine and extend axially outwardly from the trimming die, and the vertically linear path is necessary to deposit the stacks on the underlying conveyor, and then withdraw without disturbing the lateral orientation of individual plates in the stack which do not nest deeply and can be easily displaced. The return path is identically in reverse. It is when the grippers on the receiving or transfer head are intermeshed with the members forming the chutes of the trimming machine, that the grippers are operated to assume a radially contracted position, and it is when the stacks are deposited on the take-away conveyor that the gripper members are operated to assume an expanded position which results in the release of the stacks to the take-away conveyor.
One of the prime objects of the invention is to design a transfer arm-receiver head assembly which can be driven in timed relation with the operation of a trim press in a continuous manner, such that when stacks of articles are available in the trim press chutes, the receiver head is in axially oriented relationship with the chutes with the grippers in position to radially contract and grip the stacks of plates.
A further object of the invention is to provide a relatively simple, economical, and yet reliable machine for accomplishing the transfer function.
Still a further object of the invention is to design a positively controlled unit in which the required path of movement of the stacks of articles is maintained.